Mechanism and kinetic model for glycerolysis of shellac

Abstract

Shellac is a resin which is secreted from Kerria lacca, that can be utilized for coating and polyester. This material is brittle and stiff, hence modification of shellac is needed. One alternative to change its properties is by modification with glycerol. The purpose of this study is to investigate reaction between shellac and glycerol in the absence of catalyst. Moreover, in this research, the effect of hydroxyl position of glycerol is studied. In this present work, reaction was carried out for 2 hours and samples were taken every 15-30 minutes for analyzing the residual glycerol. Residual glycerol was analyzed using the periodic acid method. The reaction was carried out at various temperatures (160°C, 170°C, 180°C and 200°C). The results showed that glycerolysis reaction could be undertaken between 160°C - 180°C. In addition, the effect of ratio between glycerol and shellac was also investigated. In this study glycerol:shellac ratios were = 1:1; 1.5:1; and 2:1. The average relative error between experimental data and model in various temperature is 8.79%, while in the various ratio of glycerol and shellac is 8.26%. It showed that the kinetics model can describe well the reaction between glycerol and shellac.